Although anticancer agents are one of the three major cancer therapies along with surgery and radiation therapy, it often causes severe side effects. In general, potent anticancer agents have stronger side effects. Accordingly, physicians and patients are forced to make a rough choice in regards to the use of anticancer agents.
From such background, several methods for alleviating the side effects of anticancer agent have been proposed. For example, a method of prescribing a Chinese herbal medicine such as Shiquan Dabu teapills, a method of controlling the administration timing of the anticancer agent based on chronobiology, and a method of performing a large-scale transfusion during anticancer agent administration to protect the organs are being performed. However, the effect of alleviating the side effects of anticancer agent is still insufficient even with these methods. In addition, hospitalization is necessary for performing nighttime infusion or large-scale transfusion etc., causing a large burden in both physical and medical economical terms.
Moreover, as a method for alleviating the side effects of anticancer agent, development of agents that allow reduction of side effects are also under progress. As such agent, edaravone which is a cerebral ischemic therapeutic was acknowledged to have an alleviating action on the side effects of cisplatin on renal function, thus gathering much attention. However, this agent was found during development to have severe side effects including death caused by renal failure, and was not put on the market.
In the first place, what are the actions of anticancer agents? What is the mechanism of the side effects of anticancer agent to occur? Numerous anticancer agents already exist, and the action mechanisms of anticancer agents are being researched. Many anticancer agents show anticancer action by inhibiting DNA replication or cell cycle. Such anticancer agents show a more potent growth suppression effect on cancer cells with faster growth. On the other hand, however, because it shows similar growth suppression effect on normal cells, it also shows damage to hair roots and the intestinal tract which have fast growth among normal cells. This causes the side effects of anticancer agent.
Moreover, a type of anticancer agents suppresses and kills cancer by producing reactive oxygen species. On the other hand, the reactive oxygen produced by the anticancer agent will cause harm to normal cells not to a small extent, and this causes side effects. Administration of an antioxidant is conceivable as a method for alleviating this type of anticancer agent side effect. However, it is obvious that an antioxidant will attenuate the essential anticancer effect of the anticancer agent. Further, even if the antioxidant can alleviate this type of anticancer agent side effect, it will not be able to alleviate other types of anticancer agent side effects.
As described above, potent anticancer agents have stronger side effects. To put it conversely, anticancer agents with little side effects do not have much anticancer effect. In addition, agents that suppress the side effects of anticancer agent will also suppress the anticancer effect of anticancer agent. Molecular target drugs appeared with flourish as ideal anticancer agents to escape this dilemma. However, even without seeing the case of interstitial pneumonitis with Iressa, molecular target drugs have also not escaped from the problems of their side effects. Moreover, molecular target drugs are extremely expensive without exception.
From such background, the development of a truly effective prophylactic and/or therapeutic agent for side effects of anticancer agent has been yearned by physicians and patients. The development of a truly effective prophylactic and/or therapeutic agent for side effects of anticancer agent has also been yearned as a social demand carrying the burden of expensive healthcare cost.